There are a wide variety of known aggregate and sand treatment systems and methods, including such for treating used fraccing sand.
Aggregates include granular materials, either naturally obtained or manufactured, and constitute an important component of infrastructure. Some natural aggregate resources are sand, gravel and crushed stone. Secondary aggregates include by products from industrial processes like blast, electric furnace slags or china clay residues. Development and extraction of natural aggregates can be significantly influenced by constraints such as urbanization, zonal regulations, increased costs and environmental concerns.
Natural aggregates include fragments, e.g. of stone, rock or sand, that are used in their natural state, or are used after mechanical processing such as crushing, washing, and sizing. Crushed stone and sand, and gravel are two sources of natural aggregate, which are used directly in construction or as a raw material for construction products such as concrete and bituminous road materials. Natural aggregate materials also serve as a major source for fracturing sand.
‘Fracturing sand’ or ‘Frac sand’ is typically a high-purity sand with very durable and round grains. They are of a specific size and are highly specialized for the oil industry. Primarily it is used in the hydraulic fracturing process known as “fracking” to assist in producing or extraction of petroleum fluids such as oil, natural gas and natural gas liquids from rock units that lack adequate pore space for these fluids to flow to a well. Based on the trend of increasing oil prices coupled with natural gas and oil exploration in the Western and Eastern United States, demand for frac sand had increased in the recent years. Methods for mining and preparing frac sand may vary slightly based on deposit location and quality of deposit.
Frac sand is often produced in a range of sizes from as small as 0.1 millimeter in diameter to over 2 millimeters in diameter depending on usage requirements. The characteristics of a high quality frac sand which can be used as a petroleum industry proppant include high-purity silica sand, standard grain size, spherical shape, turbidity, acid solubility and durability to resist crushing forces of closing fractures. Traditionally, the aggregate materials are processed into frac sand by running the cleaned aggregate particles across a large shaker screen of approximately 250 sq ft size, the shaker screens are operated using large electric motors, which resulted in space consumption and increased operation costs.
From the prior art, there exists numerous patents relating to aggregate and to frac sand processing apparatus and methods. For example: US patent publication no. 20140037962A shows an apparatus and a process for producing frac sand having a predetermined size range and sphericity from a feedstock material. US patent publication no. 20130233545 shows a manufacturing process of self-suspending proppants for hydraulic fracturing. U.S. Pat. No. 8,235,313 B2 discloses a method of making spherical proppant having a selected grade from naturally occurring, mined granular minerals. US patent publication no. 20140044967 shows a system for producing and processing an aggregate. US patent publication 20120068381 shows a mobile factory for stone making and concrete processing from natural aggregates. U.S. Pat. No. 7,380,674 discloses a method of processing and sorting aggregate material using a processing device. U.S. Pat. No. 2,146,405 shows an aggregate processing apparatus. However, certain existing aggregate processing devices also comprises limitations including infrastructure, apparatus size, operational complexity, inner plate wearing, complex machinery and the like; and certain existing frac sand processing or production devices comprises limitations including large screen size, operational complexity, high operational costs, complex machinery involving electric and/or mechanical parts, and the like.
Various processes for mining aggregate materials involve an old and known rough and abrasive process. Whether the reclamation of aggregate material is carried out via a dry mining process or a wet mining process, there still exists a need to separate dust, silt, clay or finely divided organic and inorganic material from the aggregate material. In addition, for certain applications, rounding or smoothing of the aggregate material edges is desired for providing aggregate material with uniform particulate size.
Accordingly, there exists needs for: effective and efficient systems and methods for treating aggregate materials, and, in there is a particular need for such systems and methods for treating used fraccing sand so that it is re-usable; a need for an improved device for efficient separation of aggregate material from dust, silt, clay and other unwanted materials and also polishing or smoothing the aggregate material surface to achieve a uniform particle size; and a need for an improved device and method for efficient processing of aggregate material into frac sand with uniform grain size, at high throughput.